This invention relates to a dental implant.
It is publicly known that an implant acts as an artificial dental root for a denture by implanting it in the alveolar bone in order to repair a damaged tooth by implanting a denture.
Heretofore, various kinds of implants have been proposed and this invention has been anteceded by a blade-type implant.
The blade-type implant is constructed by a blade-like body and a pillar head projected towards the upper end of the body. In this case, an action which supports the denture exposes the head of the body at the time when the body is implanted in the alveolar bone.
In implanting the implant, a groove which fits the size of the implant is dug out in the alveolar bone. Then, by inserting the implant therein, an initial fixation due to friction combination is obtained, and then bone tissue in the alveolar bone increases over time and the slit between the implant and the groove is buried and connected by new raw bone. In other words, a bone setting is performed.
Thus, in the implant of the blade type, the connection of the bone by new raw bone is delayed.
However, the above conventional implant has the following problems:
(1) It is necessary to provide a groove which exactly fits the implant into the alveolar bone in order to obtain a secure initial fixation, and this operation is very difficult because it is performed in the patient's mouth. For instance, if the groove is larger than the implant, the implant wobbles, making the initial fixation inferior, and if the groove is smaller, the insertion of the implant is impossible. PA1 (2) As a result, a secure initial fixation of the implant is impossible. In order to repair the denture, it is necessary to wait until the implant is connected to the alveolar bone through the lapse of time. Accordingly, two separate operations are required. PA1 (3) In case (1), even if the implant fits the groove and does not wobble, its connection depends on the friction holding the implant in the groove. Accordingly, the implant buried by ultrasonic wave movement due to a high frequency vibration from a turbine could float up to the surface whereby cutting by a turbine cannot be performed near an area where the implant operation is practiced. PA1 (4) In case (1), although the friction force becomes stronger against the implant if the groove is smaller somewhat, there exists the peril that the alveolar bone, which is forcibly widened by the implant at the time of insertion, will split. PA1 (5) In case (1), if the contact area between the implant and the groove increases, the friction force becomes stronger. However, in this case the implant cannot enlarge its size in a total length direction in relation to the adjacent teeth, but only enlarges in the upper and lower directions. As a result, it is necessary that the groove of the alveolar bone be dug close to the jaw hole and the lower alveolar canal, and a greater risk accompanies such an operation. PA1 (6) Since a leg at the lower end of the implant gets into the alveolar bone, particularly into spongy bone having a soft tissue, when the implant is inserted into the groove by striking the implant with, a mallet at the time of implantation, the implant can sink in more than necessary. In addition, the implant can be sunk down by bite pressure even after completion of the operation.
As described above, many difficult problems are related to adopting the implant to a clinic, and the use of the implant is therefore low in Japan.
However, on the contrary, it is very useful in repairing damage to a cheek tooth or a long span bridge. In addition, there are a great many potential demands from patients who have strong aversions against dentures, and an improvement in dental implants is desired from the dental profession.